1. Field of the Invention
The invention relates to an electro-mechanically operated pump for feeding fuel, at a substantially constant pressure of several atmospheres, to supply ducts of a fuel injection system of a spark-ignition internal combustion engine.
2. Description of the Prior Art
Electrically-operated fuel pumps are known in which the impeller of a rotary pumping assembly is arranged to be driven in rotation by a small electric motor such as to cause a fuel to be fed from the fuel tank to the fuel injection system, the capacity of the pump being sufficient to cope with the largest fuel consumption rate which the engine may demand. Such pumps may incorporate a pressure-relief valve to prevent excessive pressures building up in the pump due to a malfunction in the fuel injection system.
Pumps of this type which are in current production generally suffer from one or more of the following problems:
difficulty in assembly of the parts of which the pump is composed coupled with high costs of assembly due to the necessity of assembling the components of the pump in several stages; PA1 difficulty of centering the axes of rotation of the small electric motor and the impeller of the pump; and PA1 difficulty in positioning and dimensioning the pressure relief valve both considered as a single unit and as a component of the pump as a whole. PA1 a tubular casing with respective means defining a fuel input at one end of said casing and a fuel output at the opposite end of the casing, PA1 a spindle and two spaced supports mounting the spindle longitudinally within said casing, PA1 an electric motor housed within said casing and comprising a stator and a rotor carried on said spindle, PA1 a pumping assembly arranged within said casing and including a rotatably mounted impeller, said impeller being supported on said spindle and being drivingly coupled to the rotor of the motor, PA1 electrical connection means for supplying electric current to the said motor, and PA1 first valve means for preventing the build up of excessive pressure in the fuel contained in the casing, and second valve means for preventing the return flow of fuel back through said fuel output, said casing as well as serving as a containment member for the fuel and a mechanical support structure for the components of the pump, also constituting the magnetic frame of the stator of the electric motor.
It is an object of the present invention to provide an improved electric fuel pump.